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Room rental yield calculator Compare letting by the room with letting the whole flat

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Result: Positive cash flow and ROI ≥ 5%

3-bed flat · Valencia (by the room)

Positive cash flow and ROI ≥ 5%
Valencia (Comunitat Valenciana) · Provincial capital€140,000 · €2,000/m²70 m² · 3 bedLong-term letRent €1,260 /month · €18.0/m²€1,173 /month on average, after empty months and arrears

With these figures, the rent covers the mortgage and costs, and the money you put in returns 5% or more a year.

Net monthly cash flow. What you keep each month after paying costs, the mortgage and tax. If it's negative, you top it up from your own pocket.
€366
€4,394 a year, after tax
Gross yield. Annual rent divided by the purchase price, without costs or taxes. Good for quick comparisons, not for deciding.
10.26%
Annual rent / price
Return on equity invested. Cash-on-cash: year-1 net cash flow divided by all the money that comes out of your pocket (deposit, taxes, costs, refurbishment and furniture).
7.7%
€56,850 put in
IRR over 10 years. IRR (internal rate of return): the equivalent annual return of all your cash flows, including the final sale net of costs, taxes and debt.
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Letting by the room

When letting a flat by the room pays off

By the room you collect more in total than for the whole flat, but you also spend more: utilities are usually on you, tenants change more often and there is more wear and tear. To know whether it pays, compare what you keep, not what you collect.

Reviewed on 9 October 2026

The same flat, whole or by the room

3-bedroom flat at €140,000, with the example mortgage. Whole: €1,000 a month. By the room: €420 each (€1,260 in total). «With its costs»: let 90% of the year, €1,800 a year in utilities and internet, maintenance at 6% of income and €3,000 more in furniture.

Whole flatBy the room, rent onlyBy the room, with its costs
Income for the year€11,172€14,077€13,336
Costs for the year€2,287€2,403€4,440
Income tax for the year€308€726€264
Monthly cash flow€169€366€173
Return on the cash you put in3.6%7.7%3.5%
IRR over 10 years11.5%14.9%10.9%

How it is worked out

  • Income = the sum of what you charge for each room × the months it is occupied. Allow for the odd empty month between tenants.
  • Costs = those of the whole flat (property tax, service charges, insurance, maintenance) + utilities and internet, which you usually pay + more repairs and furniture, because there are more people and more changes.
  • In the calculator above the monthly rent is the sum of the rooms. Without an account, the other figures are those of the whole flat: that is the «rent only» column. With a free account it also uses the costs of letting by the room (the last column) and you can change them: occupancy, and utilities under «Other costs».

How much do you need per room for it to pay off?

If you only change the rent, letting by the room looks much better: €366 a month against €169. With the real costs it comes to €173, almost the same. For this flat you need about €418 per room (€1,254 in total, 25% more than the whole flat) just to break even.

It pays off in cities with strong demand for rooms (students, workers on assignment) and in large flats, where each extra room adds a lot and the fixed costs are shared. In a small flat, or if you will not run it yourself, letting the whole flat is usually better.

Contracts, tax and rules

  • One contract per room, stating what is included (utilities, shared areas) and the house rules.
  • Income tax: the Spanish tax authority accepts the 50% reduction for residential lets when each room is the tenant's main home and you can prove it (binding ruling V0412-25 of the Dirección General de Tributos). If you let by the month or only for the academic year, it is usually treated as seasonal and gets no reduction.
  • Single Register: if you advertise it on platforms as a short-term let, since 1 July 2025 it also needs the register number.
  • Catalonia: since 2026, in high-demand areas the rooms together cannot exceed the maximum rent for the whole flat (Law 11/2025; it has been challenged before the Constitutional Court but remains in force). Also check whether your town hall sets conditions for shared flats.

Frequently asked questions

Is it more profitable to let by the room or the whole flat?

You collect more, but you spend more. In the example, 3 rooms at €420 (€1,260 in total) leave €173 a month after utilities, empty months and tax, almost the same as the whole flat at €1,000 (€169). It pays off if you can charge quite a lot more per room or the flat has many rooms.

How much should you charge per room for it to pay off?

Enough to cover the extra costs. For the example flat, about €418 per room just to match the whole flat; above that, you earn more.

How is letting by the room taxed?

Under income tax, like any rental. You can apply the 50% reduction if each room is the tenant's main home and you can prove it; if it is a seasonal let, you cannot.

What costs come with letting a flat by the room?

Those of the whole flat (property tax, service charges, insurance, maintenance) plus utilities and internet, which the landlord usually pays, more furniture, more repairs and the odd empty month between tenants.

Can I work it out with this calculator?

Yes: enter the sum of the rooms as the monthly rent. With a free account you can also enter the real occupancy and the utilities under «Other costs» so the sums are complete.

Cash flow/mo€366
ROI on equity7.7%
Gross yield10.26%